Missing grant type label on PKCE consent requests

The oauth event record call in the [PKCE Consent Request](https://github.com/DLMousey/OIDC.Core-Redux/blob/2dd1ed858d7c0dfdae100672043c81a802dbb4d1/OIDC.Core-Minimal/Controllers/OAuthController.cs#L305) method doesn't seem to be submitting the `grant-type` label to the metrics.

Technically there's no grant type here since it's the first leg of the oauth flow and it's just generating the consent page, another tag might need adding [oauth events class](https://github.com/DLMousey/OIDC.Core-Redux/blob/master/OIDC.Core-Minimal/Util/Metrics/OAuthEvents.cs) to handle this, same would apply to the authorization code flow.